The usual magnifying glasses designed to assist visually handicapped persons in the reading of written or printed texts comprise a unitary or cemented lens member of positive refractivity, or possibly several such lens members coaxially disposed with intervening air spaces, which must be held at a certain distance from the eye and from the text to be read. Since the eye has to be substantially in line with the optical axis, which in turn should be more or less perpendicular to the paper or other surface bearing the text, the reader normally will have to hold the magnifying glass in one hand while using the other hand for keeping the paper at a suitable inclination to the horizontal; otherwise, i.e. if the reader has only one hand free and if no inclined support for the paper is available, he will have to bend over the desk or table on which the paper is horizontally positioned. Both modes of use are inconvenient, especially for elderly persons for whom such reading aids are primarily designed.
Cylindrical magnifying lenses are also known which can be placed directly on the paper so as to overlie one or more lines of the text to be read. These devices, however, do not magnify in the longitudinal direction of the lines and generally have only a low magnification factor in the transverse direction.